Relief jet aperture swim fins with living-hinge blade

ABSTRACT

A fin and a method providing thrust from an unusually low drag kick by a swimmer are disclosed. The fin includes a fin for use by a swimmer comprising a foot pocket adapted to receive a foot of the swimmer; a foil shaped blade extending from the foot pocket; composite hydrodynamic flex control framework configured to allow the blade to bend within a narrow range of angles of attack under a wide range of loads while enhancing hydrodynamic performance. The method comprises providing a fin comprising a foot pocket, a foil shaped blade, an aperture, and two living hinges positioned adjacent to foot pocket. The method also comprises bending the blade relative to the foot pocket about an axis that is nearer the heel of the swimmer to reduce centrifugal forces while controlling the bending of the blade by providing living hinges formed to increase resistance as kicking power increases. This method additionally allows low drag kicking by a swimmer that is similar to walking in place with the swimmer&#39;s feet staying within the swimmer&#39;s slip stream.

CROSS REFERENCES TO RELATED APPLICATIONS

This invention draws upon provisional application number 60,864,459filed Nov. 6, 2006.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention is not related to a federally sponsored research ordevelopment project.

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

This invention is not the output of a joint research action oragreement.

REFERENCES TO APPENDICES ON A COMPACT DISC AND ANINCORPORATION-BY-REFERENCE OF THE MATERIAL ON THE COMPACT DISC

This application does not include compact discs or related files.

FIELD OF THE INVENTION

The present invention relates to a swim fin, comprising a seat for thefoot, the so-called foot pocket and a propelling blade (or propellingblade and propelling tail fin) with an advanced design with improvedcontrol of the bending of the blade through the formation a relief jetaperture in a portion of the blade of the swim fin that surrounds andfrees the toe section of the foot pocket from immediate contact with theblade. Various types of relief jet apertures are known but none surroundthe toe section of the foot pocket to release that section of the footpocket from the blade. Beyond the hydrodynamic gains from the relief jetaperture, this aperture releases the toe section when the blade formstwo living hinges connecting to the left and right side of the footpocket closer to the ankle than the toe section thus enabling anadjustable flexibility of the blade to produce a better angle of attack,to produce a means of adjusting the power as needed for bending theblade for different types of uses without changing the materialcomposing the blade or changing any part of the foot pocket or bladeexcept for the aperture, and to produce a curvature of the blade that iscloser to the ankle of the swimmer's foot thus reducing the effortneeded to flex the blade no matter what size or what configuration theblade may take.

BACKGROUND OF THE INVENTION

Swim fins are generally known and typically include a foot pocket and ablade portion. A desirable feature of a swim fin is that the bladeportion of the fin easily attains a correct “angle of attack”. The angleof attack is the relative angle that exists between the oncoming flow(i.e., direction of motion of the swimmer) and the actual lengthwisealignment of the blade of the fin. A “correct angle of attack” optimizesthe conversion of kicking energy of the swimmer to thrust or propulsionthrough the water (and in the case of a tail fin maximizes the liftgenerated by the hydrofoil shape of the tail fin). When this angle issmall, the blade is at a low angle of attack. When this angle is high,the blade is at a high angle of attack. As the angle of attackincreases, the flow collides with the fins attacking surface at agreater angle. This increases fluid pressure against this surface forthe blade (but decreases the surface pressure for the tail fin as it iscreating lift). The propulsion is achieved either through dragpropulsion (creating a void with the blade and being pulled into thatvoid) or through lift (creating a lower pressure through the Bernoulliprinciple like an airplane wing). When using lift propulsion, theability to increase the frequency of the sinusoidal wave created by thekicking stroke while decreasing the amplitude (the distance between thefins when they are at their farthest distance apart) to generate higherthrust with reduced drag is desirable enhancement to swim finperformance.

Current and traditional fins tend to assume different curvatures to formtheir attack angles according to the direction of movement and themagnitude of the forces applied during use (i.e., the amount of energyor power in the kick and the amplitude of the kicking stroke). Designinga swim fin to provide a particular angle of attack for a particularamount of power is generally known. One way to design a fin for aparticular kicking power is to alter the composition of the material(e.g., stiff material for hard kicking, flexible or soft material forlight kicking, etc.). Changing the composition of the material, however,does not efficiently or adequately control the angle of attack becauseof the unknowns manifested in compliant geometry. Most existing fins canonly reach a compromise in that they are either stiff, soft, orsomewhere in between. When conventional fins are designed for hardkicking (e.g., made of stiff material), they reach the correct angle ofattack when kicked very hard. On a normal, relaxed kick they don't bendfar enough and this negatively affects the performance. Fins of thiskind will be uncomfortable on the legs, strenuous and with poorperformance on a relaxed dive. When conventional fins are designed forlight kicking (e.g., made of soft material or made with large vents orsplits), they reach the correct angle of attack when kicked very gently.With a strong kick, such as when swimming in a current or needing to getup to speed, the blade is overpowered and there is little or no thrustavailable because a small void is created poorly. Fins like this mightbe comfortable on a relaxed dive, but could become unsafe by not beingable to provide the thrust to overcome a slight current. Whenconventional fins are somewhere in between, they can be overpowered whenkicked real hard, are still uncomfortable when kicked gently, but covera wider range of useful kicking power.

When such known fins are used outside their prescribed kicking power,the angle of attach tends to be too low or too high. When the fin bladeis at excessively high or low angles of attack, the flow begins toseparate, or detach itself from the low pressure surface of the fin.This tends to cause the fin to be less efficient. Another problem thatoccurs at higher angles of attack is the formation of vortices along theouter side edges of the fin. This tends to cause unwanted drag. Dragbecomes greater as the angle of attack is increased. This reduces theability of the swimmer to create a significant difference in pressure(by creating a void) between its opposing surfaces for a given angle ofattack, and therefore decreases the power delivered by the fin.

Most swim fins have reinforcing ribs for the blade to help give thegenerally flat flexible material of the blade enough structural supportso as to give an appropriate amount of flex for the blade. Some bladeshave splits to allow the water to flow through with less resistance andsome are longer and some are shorter. Some blades are foil shaped toincrease the laminar flow over the surfaces, but most are simply flatplanes with supporting ribs. The large majority of fins historicallyproduced and in use at present are the closed-toed variation of footpockets. All fins have compliant geometry in common. This field ofscience tells us how elastic and flexible materials change theirelasticity and their flexibility when their shapes are changed. Thishelps to complicate fin design compounded onto the complexity of fluiddynamics. However, certain designs lend themselves to practicalempirical examination and improvement if the areas of flexibility can belimited to a smaller area allowing easier adjustment of the compliantgeometry of the fin.

Even with “relief vents” (vents adjacent the front end of the footpocket such as with the ScubaPro Twin Jet fins), the blade starts itscurvature in front of the toes of the foot pocket. McCarthy's U.S. Pat.No. 6,884,134 has an extensive description of the prior art as of its2003 filing. In this overview of the art, it is clear that theclosed-toed foot pockets presented there, composing a broad review ofthe art, consistently have blades whereby the blades several inches infront of the toe section of the foot pocket. This increases the effortneeded to use these fins in comparison to the same blade that would beallowed to flex to the proper angle of attack closer to the heel of theswimmer. Any work done further from the heel takes more energy becauseof centrifugal forces. This principle is disclosed and better explainedin Melius U.S. Pat. No. 6,893,307.

Other swim fins may have vents or apertures in front of to the toesection of the foot pocket. These vents or apertures have been designedto relieve some of the water pressure on that part of the blade andpossibly to enhance water flow over the blade. The vents or apertures donot free the toe section from the plane of the blade so that it can moveaway from the plane of the blade. Thus, the blade works to stiffen thetoe section so that it will not break towards the toes of the swimmer asis disclosed later in this patent. These swim fins are difficult to bendnear the foot pocket because the closed-toed foot pocket generally hasthe shape of a truncated irregular cone to help seat the foot. Thistruncated irregular cone shape for the foot pocket is very difficult tobend or deform even with the use of soft flexible materials because thistype of geometric shell acts something like an arch. It doesn't bendevenly, but rather breaks at crease causing undue pressure on the toesof the user. Thus, the vast majority of swim fins are stiffened by thefoot pocket so that the blade will flex on an axis several inches downthe blade away from the foot pocket.

It is also apparent that open-toed foot pockets flex further down theblade from where the toes protrude from the foot pocket. In someopen-toed variations of foot pockets for swim fins such as thosedisclosed in Melius' U.S. Pat. Nos. 6,893,307 and 7,083,485, the bladehas an axis of flexing somewhat closer to the heel as is disclosed inmore detail later in this patent. In this case, the intersection of thefoot pocket with the blade still needs a certain amount of increasedstiffness because it can develop material failures at this intersection.Because the material finds an edge at this intersection, stress on thisedge can start rips in the material. The swim fins found in Evans' U.S.Pat. Nos. such as 6,354,894; 5,417,599; and 4,857,024 all have bladeswith open-toed foot pockets, but the blades are designed andfunctionally bend in front of the toes of the swimmers to relieve thestresses that would otherwise rip the material at the intersection ofthe foot pocket and the blade. The blade foot pocket interface has to bestiff to withstand the forces of flexing during normal use at thatintersection, and this limits the flexibility of the blade near thisintersection.

Thus, it would be advantageous to provide a swim fin that provides adesired or optimum angle of attack for a range of kicking strengths anda variety of amplitudes (the distance that the fins travel from oneextreme to the other during one cycle in kicking) in the kicking stroke.It would further be desirable to provide a swim fin in which the angleof attack is accurately controlled both for the upstroke and for thedownstroke so that the ratio of power to fin area is markedly increased(which makes it possible to reduce the overall size of the swim finwithout sacrificing total power) for various kicking efforts. It wouldfurther be advantageous to be able to change a small portion of the finto better be able to adjust the performance characteristics of the binthrough compliant geometry through empirical testing thus allowing thealtering the mold with a relatively inexpensive insert for the mold inthe manufacturing process to create a larger or smaller relief jetaperture to alter the fin for various types of kicking strengths andenergies because this would be advantageous by controlling the angle ofattack by structural characteristics of bending and not by altering thecharacteristics of materials which would enhance the empirical controlof bending of the blade. It would further be desirable to provide a swimfin with living hinges that increase the performance by controlling theangle of attack and converting a higher percentage of the kick energyinto thrust while reducing the energy needed to deform the blade intothe proper angle of attack. It would further be advantageous to providea swim fin with flow characteristics that pull the water into the centerof the blade (and tail fin when a tail fin is used) and providesimproved water flow characteristics by reducing drag through thegeneration of side vortices. It would further be desirable to have aswim fin that increased speed and thrust with an increase in smallerkicking stoke amplitudes while increasing the frequency of the stroke.It would further be desirable to provide for a swim fin having one ormore of these or other advantageous features.

To provide an inexpensive, reliable, and widely adaptable swim fin withimproved angle of attack (for both non-lift-generating surfaces andlift-generating surfaces such as foil shaped blades and tail fins),improved efficiency achieved through moving the axis of the curvature ofthe blade closer to the heel of the swimmer, improved methods forswimming with lower drag kicking techniques and through water flowcharacteristics that avoids the above-referenced problems wouldrepresent a significant advance in the art.

SUMMARY OF THE INVENTION

The present invention relates to a swim fin for use by a swimmer. Thefin comprises a foot pocket with a toe section adapted to receive a footof the swimmer, a foil shaped blade extending from the foot pocket, anda composite hydrodynamic flex control framework with at least oneaperture and with two living hinges to deform as the blade bendsconfigured to allow the blade to bend within a narrow range of angles ofattack under a wide range of loads.

The present invention also relates to a swim fin for use by a swimmer.The fin comprises a foot pocket adapted to receive a foot of theswimmer, a blade extending from the foot pocket, and a compositehydrodynamic flex control framework configured to allow the blade tobend closer to the heel than the toes of the swimmer within a narrowrange of angles of attack requiring less effort under a wide range ofloads. The wide range of loads comprises a light kick, a medium kick anda hard kick. The composite hydrodynamic flex control framework comprisesa jet relief aperture as an aperture that along with a jet relief bevelseparates the toe section of the foot pocket from the blade creatingliving hinges on the left and right side of the blade that controls theangle of attack of the blade with managed control of energy storage andthe return of said stored energy to the blade.

The present invention further relates to a swim fin for use by aswimmer. The fin comprises a foot pocket adapted to receive a foot ofthe swimmer, a blade extending from the foot pocket, and a means forreleasing the toe section of the foot pocket from the blade and a meansfor controlling flexing of the blade closer to the heel of the swimmerthan the toes.

The present invention further relates to a method of providing thrustfrom a kick by a swimmer. The method comprises providing a swim fincomprising a foot pocket, a blade, and one or more apertures thatgenerally surround the toe section of the foot pocket, and one livinghinge on the left side and one living hinge on the right side of theblade intersecting the foot pocket. The method also comprises bendingthe blade relative to the foot pocket about an axis and controlling thebending of the blade by providing increased resistance by the livinghinges as the kicking power increases while the swimmer keeps theswimmer's feet in line with the swimmer's body and thus within the slipstream of the swimmer's body thus reducing drag. This kick is unusuallysmall compared to traditional kicks with the swimmer needing only tomove the swimmer's knees and feet as much as is needed for walking. Ineffect, the swimmer has a kick that is “walking-in-place” and one thatreduces drag dramatically that is located closer to the heel of theswimmer than the toes of the swimmer and controlling the bending of theblade by providing increased resistance by the living hinges as thekicking power increases.

The present invention further relates to various features andcombinations of features shown and described in the disclosedembodiments. Other ways in which the objects and features of thedisclosed embodiments are accomplished will be described in thefollowing specification or will become apparent to those skilled in theart after they have read this specification. Such other ways are deemedto fall within the scope of the disclosed embodiments if they fallwithin the scope of the claims which follow.

Therefore, the present invention has the purpose to improve, by the useof a jet relief aperture and living hinges incorporated into the blade,a fin such as the one described hereinbefore, to better achieve aconsistently successful angle of attack for the blade with less effortunder a wider use of energetic kicking strokes while releasing the toesection of the foot pocket and causing the curvature of the blade tobegin closer to the ankle of the swimmer.

DESCRIPTION OF THE FIGURES

FIG. 1 is top plan view of a swim fin according to a preferredembodiment. (Introducing parts: 10 fin; 12 foot pocket; 13 toe section;14 blade; 15 interior CAD contour lines; 16 relief jet aperture; 17leading edge; left-side living hinge 18; right-side living hinge 19;relief jet aperture bevel 20; buckle boss 22; first end 24; second end26; center line 28; left side 30; right side 32; water drain 34; axis36.)

FIG. 2 is a top perspective view of the fin of FIG. 1 with a tail fin asan exemplary alternative embodiment. (Introducing parts: 38 peduncle; 39leading edge; 40 tail fin.)

FIG. 3 is a bottom plan view of the fin of FIG. 2. (Introducing part: 41alternate water drain.)

FIG. 4 is a side elevation view of the fin of FIG. 2.

FIG. 5 is a top perspective view of the fin of FIG. 2 with enlargedrelief jet aperture and buckles and a strap as an exemplary alternativeembodiment. (Introducing parts: 42 strap; 44 buckle.)

FIG. 6 is a top plan view of the fin of FIG. 1 with flexible flaps as anexemplary alternative embodiment. (Introducing part: 46 flexible flap.)

FIG. 7 is a top plan view of FIG. 2 with peduncle, tail fin and flexibleflaps as an exemplary alternative embodiment.

FIG. 8 is a side perspective view of a fin with an open-toed foot pocketin a downward flexed position as an example of prior art axis of flex.

FIG. 9 is a top perspective view of the fin of FIG.

FIG. 10 is a side perspective view of the fin of FIG. 8 in a upwardflexed position.

FIG. 11 is a side perspective view of a fin with a water drain andrelief vents in a downward flexed position.

FIG. 12 is a top perspective view of the fin of FIG. 11. (Introducingpart: 48 relief vent.)

FIG. 13 is a side perspective view of the fin of FIG. 11 in a upwardflexed position.

FIG. 14 is a side perspective view of a fin with a water drain composedof Shore A 65 rubber with the blade flexed downward.

FIG. 15 is a top perspective view of the fin of FIG. 14.

FIG. 16 is a side perspective of the fin of FIG. 14 with the bladeflexed upward.

FIG. 17 is top perspective view of an irregular truncated cone.(Introducing part: 50 irregular truncated cone.)

FIG. 18 is a top perspective view of the irregular truncated cone ofFIG. 17 with an intersecting plane. (Introducing part: 52 blade rotationforce; 54 plane; 56 water pressure force).

FIG. 19 is a top perspective view of the irregular truncated cone ofFIG. 17 with an intersecting plane with an aperture cut in it to freethe smaller end of the cone. (Introducing part: 58 aperture, 60 rightliving hinge, 61 left living hinge, 62 right living hinge rotationforce, 64 left living hinge rotation force).

FIG. 20 is side perspective view of the fin of FIG. 2 with the blade andtail fin flexed upwards with a strap and buckles.

FIG. 21 is a top perspective view of the fin of FIG. 20.

FIG. 22 is a side perspective view of the fin of FIG. 20 with the bladeand tail fin flexed downwards.

Before explaining a number of preferred, exemplary, and alternativeembodiments of the invention in detail it is to be understood that theinvention is not limited to the details of construction and arrangementof the components set forth in the following description or illustratedin the drawings. The invention is capable of other embodiments or beingpracticed or carried out in various ways. It is also to be understoodthat the phraseology and terminology employed herein is for the purposeof description and should not be regarded as limiting.

DETAILED DESCRIPTION OF PREFERRED AND OTHER EXEMPLARY EMBODIMENTS

Referring to FIG. 1, a fin 10 is shown according to a preferredembodiment. Each fin 10 comprises a foot pocket 12, a blade 14 with arelief jet aperture 16, a left-side living hinge 18, and a right-sideliving hinge 19 that are configured to maintain blade 14 in the desiredangle of attack for a variety or range of kicking strengths or powers.

According to a preferred embodiment, foot pocket 12 and blade 14 areintegrally molded (e.g., in a single molding operation for improvedeconomics and as well as excellent performance). Alternatively, footpocket 12 and blade 14 are fused together to form an integral structure.Foot pocket 12 is shown with an open heel and buckle boss 22 forattachment of a conventional set of buckles and heel straps (shown inFIG. 8). Alternatively, foot pocket 12 includes a closed heel instead orany of a variety of conventional designs. Foot pocket 12 is preferablyformed of the same material as blade 14 for improved economics as wellas great performance. Alternatively, foot pocket 12 is formed of amaterial having a different stiffness than blade 14. For example, if thepreferred material for blade 14 is stiff, the material for foot pocket12 may be softer for increased comfort of the diver.

Blade 14 comprises a composite hydrodynamic flex control framework. Theframework is configured to provide stiffness to blade 14 and channelwater flow to create operational lift through a proper laminar flowdirecting the flow of water towards the centerline 28 of the fin 10 toreduce side vortices and unwanted drag. The framework includes aplurality of segments shown in the FIGURES as a relief jet aperture 16,a left-side living hinge 18, a right-side living hinge, a left-sideliving hinge 19 and a relief jet bevel 20. The relief jet aperture 16formed as to disconnect the toe section 13 of the foot pocket 12 fromthe blade 14 allowing the toe section 13 to move independently of theblade 14. It also allows the blade 14 to have an axis 36 that flexescloser to the first end 24 of the fin 10 than the toe section 13 of thefoot pocket 12. The relief jet bevel 20 improves the hydrodynamics ofthe flow of water over the blade 14 and while establishing the stiffnessof the blade 14 through the resistance generated by the living hinges 18and 19 at the location of the axis 36 of flex. There is at least oneaperture 16 located adjacent to the toe section 13 and closer to thesecond end 26 of the fin 10 than the axis 36 where the flexing of thefin 10 substantially occurs. The size and shape of the left-side livinghinge 18 and the right-side living hinge 19 have multiple functions inthis preferred embodiment. The living hinges 18 and 19 comprise thefirst part of the leading edge 17 of the foil shaped blade 14 providinga minimal disruption to the laminar flow of the fin 10 while alsogenerating resistance to the wide range of loads from blade 14 due totheir tapered shape as part of the foil shape of blade 14 generating anaxis 36 of flexing at the interface of the foil shaped blade 14, theliving hinges 18 and 19 and the foot pocket 12. The living hinges storeenergy and covert the stored energy into thrust. The blade 14 canalternatively be formed by an embodiment more traditionally found in artwith a flat blade and ribs, but this embodiment is a less efficienthydrodynamic embodiment (not shown). The foil shape of the blade 14 canbe better recognized through the interior CAD contour lines 15 which areshown as a grid of lines where the lines intersecting the leading edgedescribe the flow of water from the leading edge 17 towards the secondend 26 of the fin 10. The interior CAD contour lines 15 runningapproximately parallel to the leading edge 17 show changes in the heightof the blade 14 in a manner similar to the lines of a topography map. Inthis preferred embodiment, the top edge of the relief jet bevel 20intersects the foot pocket 12. The leading edge 17 of the foil shapedblade 14 slants rearwardly towards the centerline 28 of the fin 10smoothly dividing the outflowing water towards the centerline 28 of fin10 to reduce side vortices and therefore reduce unwanted drag.

Whereas, a conventional fin design allows for a progressive andrelatively consistent bending of the entire blade to somewhataccommodate a wider range of kicking powers, a preferred embodiment ofthe present invention focuses the bending action around the left-sideliving hinge 18 and the right-side living hinge 19 because of the reliefjet aperture 16 and the relief jet bevel 20 concentrates the leverage ofthe water pushing against the blade 14 on those hinges. These hingesincrease in size and therefore increase in resistance as more of thehinges are involved in the leverage. At the same time, the increase inthe laminar flow across blade 14 decreases the leverage because blade 14is being pulled against the leverage by the low pressure that is createdby laminar flow across such the foil shape of blade 14. The result isthat the rest of the blade 14 remains substantially straight in itsstructure (seen later in FIG. 11 and FIG. 12) maintaining a moreconstant angle of attack across a wider range of kicking powers. Thetapering form of a foil as is found in blade 14 in the particularlypreferred embodiment also enhances the laminar flow found in lightfluids when they pass over foil shapes and therefore generates usefullift for propelling the swimmer.

According to a preferred embodiment, blade 14 is relatively rigid orstiff so that the flexing substantially occurs about an axis 36 at aparticular region of the fin 10 which is closer to the first end 24 ofthe fin 10 than the toe section 13 so as to reduce the effort needed toflex the blade 14. This is true whether the blade 14 is a foil shape asseen in this preferred embodiment, or is a flat blade with ribs as istraditionally used. As such, blade 14 remains essentially flat duringuse and provides a regular planar surface to interact with the waterflow to form a proper laminar flow of the water to generate much desiredlift. Preferably, the foil shape of the blade 14 slants back towards thesecond end 26 of the fin and the center line 28 to direct the flow ofwater towards the center of the fin 10 to help channel the water in adesired direction and to reduce unwanted side vortices. By maintaining arelatively flat blade 14 (e.g. providing a substantially single angle ofattack for the foil shaped blade 14), and not merely at one location (asmay be the case with a relatively flexible blade which tends to have acontinuously varying angle of attack). The increased efficiency derivedfrom the use of a rigid fin and from the use of an axis 36 of flexlocated nearer the first end 24 of the fin 10 with a channeling foilshaped blade 14 permits the design of a more powerful fin that requiresless energy to use and is more efficient due to its superior use of liftthrough excellent laminar flow and allows this fin to be relativelyshorter and use less material in manufacturing.

According to a preferred embodiment, relief jet aperture 16 isconfigured to provide a release of the toe section 13 of the foot pocket12 to allow the living hinges 18 and 19 to provide an optimum angle ofattack for a variety or range of kicking powers. By controlling theangle of attack, the living hinges 18 and 19 are configured to increaseperformance and efficiency of fin 10 by converting a higher percentageof the kick energy into thrust. Additionally, the living hinges offer ameans of controlling the flexing of the blade as well as the means tostore energy and convert the stored energy into thrust. Because theliving hinges 18 and 19 permit the optimum angle of attack for foilshaped blade 14, foil shaped blade 14 provides thrust through superiorlaminar flow generating lift. Since this “sailing” effect is notdependent on creating a void to function as is the case in traditionalpaddle like blades, the frequency and the amplitude of the stroke can bedramatically reduced which also reduces drag overall for the swimmer.

According to an exemplary embodiment, the living hinges 18 and 19gradually increase the resistance to flexing or bending of fin 10 as afunction of the degree of bending itself. This allows easy kicking powerto flex the blade 14, but doesn't allow harder kicking power to overflex the blade 14 because the lower pressure created by laminar flowover blade 14 help to keep it at the correct angle of attack. This istrue with substantially harder kicking power than might be expectedbecause the harder the kick, the faster the flow of laminar water whichkeeps lowers the pressure on blade 14 while increase resistance onliving hinges 18 and 19. The difference between a soft kick and a hardkick is the amount of effort provided by the swimmer and the energytransferred from the leg to the fin and from there to the water. Theliving hinges 18 and 19 bend the fin 10 within a narrow range of anglesof attack under a wide range of loads. As such, the angle of attack isconfigured to not significantly vary under differing load conditions.Such control of the angle of attack also provides for the concentrationand storage of the difference in energy between a soft and a hard kickin the living hinges 18 and 19 of the fin 10. These particular sectionswill a first accumulate the excess energy and later on release it andtransfer it to the water for a high efficiency forward thrust. Becausethis preferred embodiment allows for a higher frequency and loweramplitude kicking sequence, the return of this stored energy isincreased over any given swimming distance. More flexes offering morereturns in any given distance traveled increase efficiency and recoveryof invested power by the swimmer. This energy accumulation is achievedwith a small change in the degree of the bending of the blade 14 so whenfin 10 is kicked gently and more frequently in smaller amplitudes, itapproaches the optimal angle of attack, and when kicked harder, theangle of attack is increased only slightly (but remains near the optimumangle of attack) as the living hinges 18 and 19 absorbs and/or storesthe additional energy.

According to a preferred embodiment, the living hinges 18 and 19 aremade of an elastic material such that the more it stretches the moreresistance it will give. Additionally, living hinges 18 and 19 havetapering shapes as part of blade 14 which preferably has a tapered shapeof a foil. This tapered shape of living hinges 18 and 19 flexes moreeasily in the thinner parts of living hinges 18 and 19 while increasingresistance as more kicking power is applied to fin 10. As such, the moreblade 14 of fin 10 wants to bend, the higher the resistance given byliving hinges 18 and 19. The living hinges 18 and 19 are configured toallow fin 10 to efficiently attain an optimum angle of attack initiallywith minimal effort. In contrast, in conventional designs, the ribsnormally found with a traditional planar blade are straight such thatupon first bending the stretched fibers would immediately commence topull hard, whereas the compressed fibers would tend to buckle because ofthe excess material not knowing where to flow. This is compounded thecloser the axis 36 is to the foot pocket 12 because of the flattenedcone shape of the foot pocket 12 adding to the compressed fibersproblem. (More clarification of this effect will be discussed later).

One source of energy loss in kicking fin 10 is the amount of water that(during the movement of the fin 10 though the water) instead of beingpushed back by blade 14, “spills over” the sides of blade 14. Such“spillover” is typically caused by high pressure fluid on one side ofblade 14 spilling over the side of blade 14 to the low pressure side.The difference in pressure multiplied by the cross-sectional area ofblade 14 provides a measure for the size of the hole that the blade willmake in the water to create “drag” propulsion. As such, the spilloverreduces the amount of thrust generated by fin 10 because the spilloveris sucked into the void created by the fin instead of the fin 10 beingpulled into the void as propulsive force. According to a preferredembodiment, spillover is reduced almost to zero because foil shapedblade 14 pulls all on-coming water towards the centerline 28 of fin 10thus effectively eliminating spillover, improving water flow, reducingturbulence and increasing laminar flow.

Also, foil shaped blade 14 eliminates the need of protruding ribsthrough the use of the living hinges 18 and 19. The foil shape of blade14 naturally creates living hinges 18 and 19 that have desirablecharacteristics that enable the hinges to flex easily in the thinnerparts of blade 14 and increase in resistance as living hinges 18 and 19get thicker due to the increase in the thickness of the foil shape ofblade 14. This enables a wider range of kicking power to be used whilemaintaining an optimum angle of attack for blade 14. The lower pressurecreated over a foil shape also helps to keep the blade from bendingfurther at axis 36 because the blade 14 is being pulled towards thelower pressure produced by laminar flow over a foil shape. This reducesdrag, reduces turbulence, reduces spillover while improving water flowand increasing laminar flow.

Referring to FIG. 1 in a preferred embodiment of fin 10, FIG. 2 shows aperformance enhancing exemplary alternative embodiment of fin 10 thatmay be considered economically less desirable because of substantialincreases in mold costs and increase in the costs due to the extramaterial used, and the increased costs associated with the manufacturingdifficulties caused by the undulating size of the peduncle 39 and tailfin 40 due to the extension of the size of the fin 10 to a larger area.However, a peduncle 39 and a tail fin 40 are configured increase speedand thrust while decreasing the effort of the swimmer through the use ofserial amplification of the flow of water over the foil shaped blade 14past the tail fin 40. This occurs because of the addition of anotherfoil shape which acts in a manner similar to adding another sail to aship. Since both foils, blade 14 and tail fin 40, induce laminar flow tocreate lift, they can work in tandem in a form of serial amplificationwhere the flow of water across the blade is increased and then crossesto the tail fin 40 for additional service to the swimmer. Thisphenomenon in described more in depth in Melius U.S. Pat. No. 7,083,485.

In FIG. 3, a secondary drain hole 41 is taught having the advantage ofdraining the foot pocket more efficiently when used in conjunction withthe preferred embodiment for water drain 34. Releasing the pressure ofthe water in the foot pocket 12 is advantageous after diving when thediver wants to remove his boot from the foot pocket 12. If no drain hole41 is provided or even better the larger water drain 34, then the divermay have serious difficulty with the boot being kept in the foot pocket12 by a suction caused by the water present in the foot pocket 12. Thisis not so much a problem out of the water, but taking your boots off inthe water can be unusually difficult with the drain hole 41 at the veryminimum.

FIG. 4 teaches the foil shape of blade 14 and tail fin 40 by the sideview revealing their contours. This information in addition to theinformation taught in FIGS. 1, 2, and 3 with the interior CAD contourlines 15 help to define the nature of the foil shapes of blade 14 andtail fin 40.

As the size and shape of the relief jet aperture is changed as seen inFIG. 5, the performance characteristics of fin 10 are also changedrather dramatically because the physical size and shape of the livinghinges 18 and 19 also change. The use of no relief jet bevel 20 istaught in this exemplary alternative embodiment where the size of therelief jet aperture allows even easier deformation of blade 14 throughthe use of smaller living hinges 18 and 19 allowing fin 10 to be usedfor medicinal purposes of physical therapy for those who need to stresstheir leg muscles without stress their joints. This can be accomplishedby having the patient float weightlessly in water and have them movetheir legs in various sets of exercises as controlled by a physicaltherapist in order to strengthen different sets of leg muscles withouthaving the legs of the patient subjected to the stresses of gravity ontheir joints. In tests, the increased flow of the water through largerrelief jet aperture 16 allowed the patient to move their leg with almostno extra drag. Secondly, a smaller relief jet aperture 16 could be usedfor a good leg enabling more serious thrust more propulsion while thelarger sized relief jet aperture 16 could be used for a leg having themedical difficulty. In patients with dramatically reduced movement (dueto stroke or brain tumors for example) in one leg, the movement of thehealthy leg caused the weaker disabled leg to move because of waterresistance. This movement of the weaker leg feels natural to the patientand is beneficial to the patient.

Referring to FIG. 1 in a basic preferred embodiment of fin 10, FIG. 6shows an exemplary alternative embodiment of fin 10 where a flexibleflap 46 is added on to blade 14 on either side of the centerline 28. Theaddition of flexible flaps 46 on the foil shaped blade 14 to enable theuse of stiffer less expensive materials for blade 14 creating a positivelaminar flow of water across blade 14 where the living hinges 18 and 19would be made of a more flexible material. Blade 14 would have advantageof longer surfaces for influencing the flow of water for generatingthrust without making it necessary to increase the cross section ofblade 14. This formation is often found in marine mammals and allowsblade 14 to be used almost in a hybrid manner as partial paddle andpartial foil.

Referring to FIG. 1 in a basic preferred embodiment of fin 10, FIG. 7shows an exemplary alternative embodiment of fin 10 that may beconsidered a combination of exemplary embodiments found in FIGS. 2 and6. This hybrid formation of hydrodynamic elements comprising flexibleflaps, a peduncle and a tail fin enhance the laminar flow of wateracross the blade and the tail fin for increased control and propulsion.

FIGS. 8 through 16 show prior art in static and flexed positions. Thelocation of axis 36 about which blade 14 flexes in fins 10 should benoticed. In all embodiments in the FIGURES, axis 36 is located in frontof the swimmers toes. This increases the effort needed to flex the blade14 because centrifugal forces are increased as axis 36 is moved furtherfrom the pivot point of the swimmer (in this case the heel of theswimmer.) Since the productive work for blade 14 begins where the angleof attack is optimum, it is optimum to move the angle of attack as closeto the pivot point of the heel as is practically possible. In thepresent preferred and alternative embodiments, we have balanced theneeds of strength, durability, and the probability that the swimmer willhit the fins together causing discomfort and other problems for theswimmer. Secondly, the choice of having axis 36 located at the ball ofthe foot of the swimmer is a natural fit. The foot of the swimmer bendsat the ball of the foot which makes that a natural choice to have axis36 of the fin 10.

FIGS. 17 through 19 teach the advantages of the composite hydrodynamicflex control framework. In FIG. 17, the irregular truncated cone 50illustrates the general shape of the foot pocket 12 because the footpocket 12 must seat the foot of the swimmer, an irregular truncated coneshape even when wearing a bootie. This irregular truncated cone 50 doesnot want to bend because it is continually under compression similar toan arch. It will “break” (form a crease along a weak area) instead ofgently spread any pressure applied to its surface. This break orcollapse causes undue stress on any part of the swimmers foot that itpresses against. In FIG. 18, the plane 54 intersects the irregulartruncated cone 50 making the irregular truncated cone even stifferbecause of the reinforcement that the plane 54 gives to the walls of theirregular truncated cone 50. Therefore, when the water pressure force 56moves the plane 54 towards the irregular truncated cone 50 a bladerotation force 52 tries to compress the irregular truncated cone 50resulting in a break or collapse in the wall causing discomfort and painto the swimmer. The traditional solution found on all other fins in theart that have closed foot pocket 12 is to have the axis 36 located infront of pocket 12 sufficiently far as not to make the irregulartruncated cone 50 collapse or break. The blade compression forceinitiates in the plane 54 in front of the irregular truncated cone 50and exerts pressure onto the sides of irregular truncated cone 50. InFIG. 19, the aperture 58 separates the plane 54 from the truncated endof irregular truncated cone 50 creating the right and left living hinges60 and 61 respectively. This dramatically changes the interaction ofplane 54 with the irregular truncated cone 50 because the blade rotationforce 52 still initiates in front of the truncated cone 50 but transfersits force to the area located in the side of the irregular truncatedcone 50 at the left and right living hinges 60 and 61. This causes rightand left living hinges 60 and 61 to experience a right and left livinghinge rotation force 62 and 64 respectively. These forces do not try tocollapse or break the irregular truncated cone 50 because they work torotate the right and left side of the irregular truncated cone insteadof trying to compress the walls of the irregular truncated cone 50. Thisdoes not translate into pressures that the foot of the diver canexperience. Additionally advantageous is the movement of the axis offlex back to the living hinges 60 and 61.

FIGS. 20 through 22 teach how the axis 36 is closer to first end 24 offin 10 than the toe section 13 of foot pocket 12. The positioning of theaxis 36 closer to the heel of the swimmer than is found in traditionalfins delivers better performance with less energy because the axis 36needs less centrifugal force for bending. FIG. 20 shows fin 10 upwardlybent with the axis 36 located closer to the heel of the swimmer when inuse. FIG. 21 shows the axis 36 crossing through fin 10 at the livinghinges 18 and 19. FIG. 22 shows fin 10 downwardly bent with the axis 36located closer to the heel of the swimmer when in use.

It is also important to note that the construction and arrangement ofthe elements of the fin with improved angle of attack and water flowcharacteristics as shown in the preferred and other exemplaryembodiments are illustrative only. Although only a few embodiments ofthe present invention have been described in detail in this disclosure,those skilled in the art who review this disclosure will readilyappreciate that many modifications are possible (e.g., variations insizes, dimensions, structures, shapes and proportions of the variouselements, values of parameters, mounting arrangements, materials,colors, orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited in the claims.For example, the energy accumulations may have any of a variety ofshapes or configurations. Also, blade 14 may be made of a stiff material(rather than the preferred flexible material) and still incorporate theadvantages of the living hinge system. Accordingly, all suchmodifications are intended to be included within the scope of thepresent invention as defined in the appended claims. The order orsequence of any process or method steps may be varied or re-sequencedaccording to alternative embodiments. In the claims, anymeans-plus-function clause is intended to cover the structures describedherein as performing the recited function and not only structuralequivalents but also equivalent structures. Other substitutions,modifications, changes and/or omissions may be made in the design,operating conditions and arrangement of the preferred and otherexemplary embodiments without departing from the spirit of the presentinvention as expressed in the following claims.

1. A fin for use by a swimmer and having a first end, a second endopposite the first end, and right and left sides extending between thefirst and second ends, the fin comprising: a foot pocket with a toesection located at the first end and adapted to receive a foot of theswimmer; a foil shaped blade extending from the foot pocket toward thesecond end; a composite hydrodynamic flex control framework with atleast one aperture and with two living hinges to deform as the bladebends; wherein at least one of the two living hinges causes the blade tobend within a narrow range of angles of attack under a wide range ofloads.
 2. The fin of claim 1 wherein the at least one aperture islocated adjacent to the toe section and closer to the second end of thefin than the axis where the flexing of the fin substantially occurs. 3.The fin of claim 1 wherein the living hinges comprise the first part ofthe leading edge of the foil shaped blade providing a minimal disruptionto the laminar flow of the fin while also generating resistance to thewide range of loads from the blade wherein their tapered shape as partof the foil shape of the blade generating an axis of flexing at theinterface of the foil shaped blade, the living hinges and the footpocket.
 4. The fin of claim 1 wherein the composite hydrodynamic flexcontrol framework is configured to store and release energy during useof the fin under a wide range of loads comprised of a light kick, mediumkick and a hard kick.
 5. The fin of claim 1 wherein the relief jetaperture is formed as to disconnect the toe section of the foot pocketfrom the blade allowing the toe section to move independently of theblade.
 6. The fin of claim 1 wherein the leading edge of the foil shapedblade slants rearwardly towards the centerline of the fin smoothlydividing the outflowing water towards the centerline of the fin toreduce side vortices and therefore reduce unwanted drag.
 7. The fin ofclaim 1 with a peduncle and a tail fin wherein the peduncle and tail finare configured to increase speed and thrust while decreasing the effortof the swimmer through the use of serial amplification of the flow ofwater over the foil shaped blade past the tail fin.
 8. The fin of claim1 with flexible flaps on the foil shaped blade to enable the use ofstiffer less expensive materials for blade creating a positive laminarflow of water across the blade wherein the living hinges would be madeof a more flexible material.
 9. The fin of claim 1 with a hybridformation of hydrodynamic elements comprising flexible flaps of claim 8,and the peduncle and the tail fin of claim 7 wherein these elementsenhance the laminar flow of water across the blade and the tail fin forincreased control and propulsion.
 10. A fin for use by a swimmer andhaving a first end, a second end opposite the first end, and right andleft sides extending between the first and second ends, the fincomprising: a foot pocket located at the first end and adapted toreceive a foot of the swimmer; a blade extending from the foot pockettoward the second end and having a major surface between the right sideand the left side and configured to flex about an axis; a compositehydrodynamic flex control framework configured to allow the blade tobend closer to the heel than the toes of the swimmer within a narrowrange of angles of attack requiring less effort under a wide range ofloads; wherein the wide range of loads comprises a light kick, a mediumkick and a hard kick, and the composite hydrodynamic flex controlframework comprises a jet relief aperture as an aperture that along witha jet relief bevel separates the toe section of the foot pocket from theblade creating living hinges on the left and right side of the bladethat controls the angle of attack of the blade with managed control ofenergy storage and the return of said stored energy to the blade. 11.The fin of claim 10 wherein the living hinges comprise the first part ofthe leading edge of the blade while generating increased resistance toincreased loads from the blade with managed control of energy storageand the return of said stored energy to the blade.
 12. The fin of claim10 with a peduncle and a tail fin wherein the peduncle and tail fin areconfigured to increase speed and thrust while decreasing the effort ofthe swimmer through the use of serial amplification of the flow of waterover the foil shaped blade past the tail fin.
 13. The fin of claim 10with flexible flaps on the foil shaped blade to enable the use ofstiffer less expensive materials for blade creating a positive laminarflow of water across the blade wherein the living hinges would be madeof a more flexible material.
 14. The fin of claim 10 with a hybridformation of hydrodynamic elements comprising flexible flaps of claim13, and the peduncle and the tail fin of claim 12 wherein these elementsenhance the laminar flow of water across the blade and the tail fin forincreased control and propulsion.
 15. The fin of claim 10 wherein therelief jet aperture is formed as to disconnect the toe section of thefoot pocket from the blade allowing the toe section to moveindependently of the blade.
 16. The fin of claim 10 wherein the leadingedge of the blade slants rearwardly towards the centerline of the finsmoothly dividing the outflowing water towards the centerline of the finto reduce side vortices and therefore reduce unwanted drag.
 17. A finfor use by a swimmer, the fin comprising: a foot pocket adapted toreceive a foot of the swimmer; a blade extending from the foot pocket;means for releasing the toe section of the foot pocket from the blade;means for controlling flexing of the blade closer to the heel of theswimmer than the toes.
 18. The fin of claim 17 with a peduncle and atail fin wherein the peduncle and tail fin are configured to increasespeed and thrust while decreasing the effort of the swimmer through theuse of serial amplification of the flow of water over the foil shapedblade past the tail fin.
 19. The fin of claim 17 with flexible flaps onthe foil shaped blade to enable the use of stiffer less expensivematerials for blade creating a positive laminar flow of water across theblade wherein the living hinges would be made of a more flexiblematerial.
 20. The fin of claim 17 with a hybrid formation ofhydrodynamic elements comprising flexible flaps of claim 19, and thepeduncle and the tail fin of claim 18 wherein these elements enhance thelaminar flow of water across the blade and the tail fin for increasedcontrol and propulsion.
 21. The fin of claim 17 wherein the means ofcontrolling flexing of the blade stores energy by deforming one or moreof the living hinges becoming a means to store energy and convert thestored energy into thrust.